Tanssion > blog > Audio Products > Buzzer: Structure, Working Principle and Parameters

Buzzer: Structure, Working Principle and Parameters

Author: Tanssion Date: 2023-08-29 Hits: 0

Ⅰ. What is a buzzer?
Ⅱ. The structure of the buzzer
Ⅲ. The working principle of buzzer
Ⅳ. The production of the buzzer
Ⅴ. Parameters of the buzzer
Ⅵ. The typical circuit of the buzzer
Ⅶ. The advantages and disadvantages of the buzzer
Ⅷ. The component selection of the buzzer circuit
Ⅸ. The difference between active buzzer and passive buzzer
Ⅹ. Precautions for using the buzzer

Ⅰ. What is a buzzer?

The buzzer is an electronic sounder with an integrated structure. It is powered by DC voltage and is widely used as a sounding device in electronic products such as computers, printers, copiers, alarms, electronic toys, automotive electronic equipment, telephones, and timers. For example, the host computer of a desktop computer will make a "beep" sound when it is turned on, and the washing machine will make a sound when the button is pressed and the laundry is completed. These are all sent by the buzzer. The buzzer is represented by the letter "H" or "HA" in the circuit (the old standard uses "FM", "ZZG", "LB", "JD", etc.).

Ⅱ. The structure of the buzzer

1. Piezoelectric buzzer structure

(1) Leads: The piezoelectric sheet is connected to the circuit through the leads. When a voltage is applied, the leads transmit the voltage to the piezo.

(2) Diaphragm: The piezoelectric sheet is connected to a diaphragm, usually made of metal or plastic material. The vibrating membrane also vibrates when the piezoelectric sheet vibrates, thereby amplifying sound production.

(3) Piezoelectric Element: This is the core element of the buzzer, usually made of piezoelectric ceramic materials, such as piezoelectric ceramic wafers. When a voltage is applied, the piezoelectric sheet is mechanically deformed, causing vibrations.

(4) Backplate: There is a backplate under the vibrating membrane, which forms a cavity with the vibrating membrane. When the diaphragm vibrates, the air inside the cavity also vibrates, producing sound.

2. Electromagnetic buzzer structure

Electromagnetic buzzers use electromagnetic induction to generate sound. The following is the main structure of the electromagnetic buzzer.

(1) Magnet: We usually place a permanent magnet or electromagnet on the other side of the oscillator to enhance the vibration effect of the oscillator.

(2) Diaphragm: The vibrator is connected to a diaphragm, usually a film-like material. The diaphragm also produces sound when the oscillator vibrates.

(3) Leads: The buzzer is connected to the circuit through the leads. Electromagnetic effects in the coil cause vibrations when current is passed.

(4) Coil: There is a coil inside the buzzer, which is usually wound by wire. When current is passed through the coil, a magnetic field is created.

(5) Armature: We place an armature near the coil, usually a piece of metal. When the coil generates a magnetic field, it exerts force on the vibrator, causing the vibrator to vibrate.

Ⅲ. The working principle of buzzer

The principle of the conventional magnetic horn is different from the generally referred to buzzer. The buzzer generally refers to piezoelectric ceramics as the main component. Piezoelectric ceramics are a type of special ceramics capable of converting pressure and current into each other. This ability is due to its special crystal structure.

When the piezoelectric ceramic is subjected to a pressure in a certain direction to deform its crystal structure, it will generate an electric current inside, and the change of the current is closely related to the change of the pressure. vice versa. Therefore, using this characteristic, passing a certain frequency of current on the piezoelectric ceramic will cause a small deformation of the piezoelectric ceramic, and this deformation will drive the air to vibrate. If the frequency is appropriate, it can be heard by the human ear, that is, a buzzing sound is produced.

Ⅳ. The production of the buzzer

1. Prepare the electromagnet M: We wind the wire 100 times, use a 6 cm long iron bolt, and leave 5 cm at the end of the wire as a lead wire. We first secured the coil with a piece of clear tape so it wouldn't come loose, and attached it to a box, thus making an electromagnet.

2. Prepare the shrapnel P: We cut a long iron piece with a width of about 2 cm from the tin can, bent it into a right angle, connected a lead wire of the electromagnet to the shrapnel, and then glued the shrapnel to the wooden board.

3. We use a paper clip as the contact Q, use a book to put the paper clip on it, then fix it with tape, and then pull out a wire to connect the circuit.

4. We adjust the distance between M and P (by moving the box), so that the electromagnet can attract the shrapnel, and adjust the distance between the contact and the shrapnel, so that the two can just touch. After power on, we can hear the beep.

Ⅴ. Parameters of the buzzer

1. Driving Method

The drive mode of the buzzer can be direct current (DC) drive or pulse drive (PWM). Different driving methods will affect the response and sound quality of the buzzer.

2. Frequency Range

The frequency range in which the buzzer can emit sound is usually expressed in Hertz (Hz). Common frequency ranges range from a few hundred hertz to several kilohertz.

3. Sound Pressure Level

The sound output level of a buzzer is usually expressed in decibels (dB). The higher the sound pressure level, the louder the buzzer sound.

4. Operating Voltage

It refers to the voltage range in which the buzzer can work normally. Common operating voltages include 3V, 5V, 12V, etc., depending on the type and application of the buzzer.

Ⅵ. The typical circuit of the buzzer

The following is a typical circuit of a buzzer, taking an active buzzer as an example.

1. NPN type transistor

Many people on the Internet use 9013 for their circuit transistors, but there is no 9013 in proteus, so they are replaced with 2N551 similar to it. When the IO is set high, the b-end voltage of the NPN transistor is 0.7V higher than the e-end. At this time, the c terminal and the e terminal are turned on, and the buzzer starts to work. The function of the 3.3K pull-down resistor is to prevent false triggering of the buzzer by I0 in an unstable state.

2. PNP transistor

2N5401 and 2N5551 are a pair of transistors with different polarities but the same properties. When the I0 terminal is pulled low, after the e-terminal voltage is 0.7V higher than the b-terminal, the e-terminal and the c-terminal are turned on, and the buzzer starts to work. The pull-up resistor is to prevent false triggering of the buzzer when the IO is disturbed.

Ⅶ. The advantages and disadvantages of the buzzer

1. Advantages

(1) Small size

(2) Less energy consumption

(3) Simple compatibility

(4) Good frequency response

(5) Large voltage range and high sound pressure

2. Disadvantages

(1) It is difficult to control the sound and frequency of the buzzer. It requires the use of specialized controllers or circuits.

(2) The sound produced by the buzzer may be annoying, especially in the case of long-term and high-frequency use.

Ⅷ. The component selection of the buzzer circuit

The buzzer circuit has a large working current and needs to be driven by an amplifier circuit. Therefore, the buzzer circuit generally includes the following components.

1. Buzzer

When you apply a passive buzzer (square wave) or an active buzzer (DC voltage) across the sounding element, the following five points are critical. These factors include form factor, operating current, direction of sound, drive mode, and operating frequency. Also, you can select the desired parameters according to your needs.

2. Triode

The transistor saturates when the base rises. Therefore, the buzzer will sound. However, as the base voltage decreases, the transistor enters the cut-off state. This way it ends the sound.

3. Filter capacitor

This component helps filter the buzzer current from the rest of the circuit and improves AC power.

4. Freewheeling diode

The buzzer is a sensing element. So you can't change its current. But you can use freewheeling diodes to constantly monitor the continuous current. Otherwise, this may damage the driving transistor, causing the entire circuit system to collapse. Without the use of freewheeling diodes, the buzzer circuit can draw high currents of tens of volts.

Ⅸ. The difference between active buzzer and passive buzzer

Passive buzzer and active buzzer are two different types of sound devices, and there are some differences in their working principle, circuit connection and usage.

1. How to use: Since the frequency of the passive buzzer is fixed, generally only a single tone can be emitted. The active buzzer can produce different tones and music effects by controlling the frequency and duration of the signal.

2. Working principle: The passive buzzer uses the piezoelectric effect to generate sound and does not require an external power source. The active buzzer needs an external power supply to drive.

3. Circuit connection: Passive buzzers usually only have two pins, which are directly connected to the circuit to emit a fixed frequency sound. Active buzzers usually have three pins. One of them is a power pin, which is used to connect an external power source. The other two are signal pins, which are used to receive control signals and generate corresponding sounds.

Ⅹ. Precautions for using the buzzer

1. Do not use the buzzer in a temperature environment other than the marked working temperature (When the buzzer works outside the marked working temperature, the performance of the piezoelectric film and the shell will change, and the sound will be low).

2. Follow the marked soldering method (Commonly used soldering methods for buzzers include manual soldering, wave soldering, and reflow soldering. Wave soldering and reflow soldering are modern automated soldering technologies. Wave soldering is mainly for plug-in products, and reflow soldering is mainly for SMD products. Because the temperature of the two soldering methods is very high, the temperature resistance data must be used for the buzzer device. Of course, products suitable for wave soldering and reflow soldering can also be stopped by manual soldering.)

3. Prevent foreign matter from entering the sound hole of the buzzer (Foreign matter entering the sound hole of the buzzer may affect the vibration of the diaphragm, resulting in tiny or abnormal sounds).

4. The non-waterproof buzzer should prevent the buzzer device from being placed in a place where it may come into contact with water (Water entering the non-waterproof buzzer will cause product parts to rust, short circuit, and vibration to be blocked).

5. Do not use the buzzer outside the marked operating voltage (Due to the spontaneous polarization of ceramics, there is a residual polarization in the ceramic after these spontaneous polarizations have been processed and forced to align by the poling process. When the voltage is too high, this polarization will cause excessive discharge and charge, resulting in an arc phenomenon. The ceramic sheet breaks and the electric field decays).


Frequently Asked Questions

1、What is buzzer used for?
A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric (piezo for short). Typical uses of buzzers and beepers include alarm devices, timers, and confirmation of user input such as a mouse click or keystroke.
2、How does an active buzzer work?
Buzzers can be categorized into two different types – active buzzers and passive buzzers. An active buzzer has a built-in oscillator so it can produce sound with only a DC power supply. A passive buzzer does not have a built-in oscillator, so it needs an AC audio signal to produce sound.
3、Can a buzzer vibrate?
Piezoelectric buzzers rely on this process to create vibrations. The buzzer applies a voltage across the piezoelectric element thousands of times per second which flexes the piezoelectric element to create noise. The pitch generated from a buzzer is called its frequency and is measured in hertz.
4、What are the advantages of a buzzer?
Advantages of a buzzer vs speaker. Piezo buzzers use minimal current so draw less power. Their current consumption is typically less than 10mA. Depending on the sound output required, they are usually a cheaper option compared to a miniature speaker.
5、What is the characteristic of a buzzer?
First, a buzzer usually has a rated DC voltage of 6V. However, its operating DC voltage ranges between 4 to 8V. In addition, it has a rated current of less than 30mA. Also, note that the buzzer has a resonant frequency of about 2300 Hz to 3300 Hz.

Leave a Comment

Related Articles

Popular Tags

PMIC Audio Products Logic Interface capacitors linear controllers embedded Line Protection drivers amplifiers Distribution Backups wireless modules memory converters Battery Products sensors filters relays Switches distribution analog Clock timing voltage diodes speakers Batteries Rechargeable battery regulators Fiber Optic Cables Cable Assemblies routers microcontroller Backups audio Magnetics - Transformer Inductor Components cables Electric Double Layer Capacitors (EDLC) Supercapa inductors transformer optoelectronics potentiometer resistors switching management special digital purpose signal Discrete Semiconductor Ceramic Capacitors semiconductor cable Alarms equipment resonators oscillators crystals kits accessories isolators motors RF Transformers monitors comparators specialized programmable microcontrollers FPGAs Data Acquisition application specific gates inverters Buffers Transceivers dividers Sensor decoders microprocessors microprocessor DC video circuit protection microphones PCB Integrated Circuits (ICs) PMIC - Lighting Memory Cards SSDs HDDs Wires Tantalum Capacitors Transducers LEDs Battery Chargers 4G Ballast Controllers Vacuum Tubes Transistors - Bipolar (BJT) - Single counter integrated circuits Guitar Parts Buzzer Elements transducers circuit Computer Equipment Piezo Benders boxes Magnetics enclosures racks Buzzers wires and Sirens wire Buzzers and Sirens inductor components connectors interconnects Embedded Computers fans thermal hardware fasteners coils chokes controls automation identification barriers signs labels protection inductor educational networking resistor powersupply power supply prototyping fabrication desoldering soldering ESD static Tapes adhesives materials Test measurement Tools Uncategorized Specialized ICs voltage Regulators contro thermal Management motor laser full half switchers batteries translators shift latches flip flops voice playback serializers deserializers active synthesis PLDs clocks delay lines reference supervisors PoE correction lighting ballast hot swap energy metering specialty parity generators checkers FIFOs multipliers instrumentation UARTs terminators capacitive touch Modems ICs Encoders DSP Data acquisition front end timers synthesizers frequency regulator controller regula RMS power OR ideal LED gate display chargers configuration proms universal bus functions multiplexers multivibrators counters processing amps telecom repeaters splitters detector interfaces I/O expanders receivers CODECs system SoC CPLDs Complex amplifier IF RFID Oscillator Externally excited oscillator fuses switchs transistors shunt thyristor Oscillators Resonators Ballast Controllers Coils Chokes RF Filters RF/IF and RFID RF Amplifiers Battery Packs SAW Filters Mica and PTFE Capacitors Accessories Piezo Benders sdsd ballasts starter SSD HDD Modules

Popular Posts